1. Field of the Invention
The invention relates to a check valve for a piston pump, particularly for use in a piston pump of a hydraulic vehicle brake system that has a traction control apparatus.
2. Description of the Prior Art
A check valve of this kind has been disclosed, for example, by DE 41 07 979 A1. The known check valve is disposed at one end of a piston that is part of a piston pump; the piston pump is provided for supplying brake fluid to a hydraulic vehicle brake system that has a traction control apparatus. The piston has an axial opening whose mouth constitutes a valve seat of the check valve. A ball disposed against the valve seat constitutes a valve closing body of the known check valve. In an intrinsically known fashion, the ball that constitutes the valve closing body rests in a sealed fashion against the valve seat when the check valve is closed and is lifted up from the valve seat when the check valve is open.
The expensive assembly of the known check valve during the assembly of the piston pump is disadvantageous; the known check valve cannot be preassembled as a unit. Another disadvantage of the known check valve is that a guide must be provided for the valve closing body.
In a check valve according to the invention, the valve closing spring is embodied as a spring clip which embraces the valve closing body, is attached to the valve seat part, and connects the valve closing body to the valve seat part in a mobile fashion. The check valve according to the invention has the advantage that its valve closing spring simultaneously constitutes a guide and a valve stroke limitation for the valve closing body. The latter means that the spring clip limits a distance by which the valve closing body can be lifted up from the valve seat. The valve stroke limitation permits a short closing time of the check valve to be achieved. The check valve according to the invention can be simply and inexpensively produced out of only three parts, is suitable for miniaturization, and is thus suitable for use as an inlet or outlet valve of a piston pump of a traction-controlled vehicle brake system. However, this is not the only potential application of the check valve according to the invention; it can, in principle, be used anywhere that backflow needs to be prevented. The check valve according to the invention constitutes a subassembly whose parts are held together and which can be stored and installed as a unit.
Our embodiment of the valve closing body has a disk-shaped component and has the advantage that when the check valve opens, it rapidly unblocks a large flow cross section which lends the check valve favorable dynamic properties.
The check valve according to the invention is provided as an inlet or outlet valve of a piston pump, particularly for connecting to an end of a piston of the piston pump. According to the invention, the piston pump is particularly provided as a pump in a brake system of a vehicle and is used to control the pressure in wheel brake cylinders. Depending on the type of brake system, these brake systems are referred to by the abbreviations ABS, TCS, ESP, or EHB. In the brake system, the pump is used, for example, to return brake fluid from one or more of wheel brake cylinders to a master cylinder (ABS) and/or for supplying brake fluid from a reservoir into one or more of wheel brake cylinders (TCS, ESP, or EHB). The pump is required, for example, in a brake system with a wheel slip regulation (ABS or TCS) and/or in a brake system used as a steering aid (ESP) and/or in an electrohydraulic brake system (EHB). Wheel slip regulation (ABS or TCS) can, for example, prevent the wheels of the vehicle from locking when there is powerful pressure on the brake pedal during a braking maneuver (ABS) and/or can prevent the driven wheels of a vehicle from spinning when there is powerful pressure on the accelerator pedal. In a brake system used as a steering aid (ESP), a brake pressure is built up in one or more wheel brake cylinders, independent of an actuation of the brake pedal or accelerator pedal, in order, for example, to prevent the vehicle from swerving out from the path desired by the driver. The pump can also be used in an electrohydraulic brake system (EHB) in which the pump supplies brake fluid to the wheel brake cylinder(s) when an electric sensor detects an actuation of the brake pedal or in which the pump is used to fill a reservoir of the brake system.